The present invention relates to a steering column device which is mounted on a vehicle, and particularly to a steering column device having a function for absorbing shock energy particularly at the time of a secondary collision caused by an occupant.
In this type of the steering column device having the shock energy absorbing function, as is well known, it is possible to perform the relative sliding operation between the outer tube of an upper side and the inner tube of a lower side, which form a steering column. When a predetermined load is exerted on a steering wheel at the time of the secondary collision of the occupant caused by the collision of the vehicle (primary collision), the shock energy is absorbed by performing the relative sliding operation between the outer tube and the inner tube.
On the other hand, a wrench might occur by exerting a load on the steering wheel from a direction other than the axial direction of the steering column at the time of the secondary collision of the occupant by the difference of a condition at the time of the vehicle collision (for example, a full-wrap frontal collision or an offset frontal collision) and the difference of the mounting angle of the steering column to the vehicle. In this case, there is a fear that a predetermined shock energy absorbing performance is not obtained. As a solution to this, for example, a steering column device disclosed in JP Patent Application Publication No. 2014-101070 is proposed.
In the steering column device disclosed in JP Patent Application Publication No. 2014-101070, the steering column device has the outer tube of an upper side and the inner tube of a lower side which relatively slide in the axial direction of the outer tube and the inner tube at the time of the shock absorption with the collision of the vehicle. In addition, a rolling element (sliding resistance reduction element), such as a cylindrical roller, is provided at each end portion of the outer tube and the inner tube. The rolling element provided at the end portion of the outer tube is brought into press-contact with the inner tube, and the rolling element provided at the end portion of the inner tube is brought into press-contact with the outer tube.
Furthermore, although an object is different from that of the steering column device disclosed in JP 2014-101070, JP Patent Application Publication No. 2010-18182 discloses a steering column device in which a rolling element is interposed between the outer tube of an upper side and the inner tube of a lower side, similar to the rolling element disclosed in JP 2014-101070 (see FIG. 14 and FIG. 17 to FIG. 20 of JP 2010-18182).